Auxiliary heater for a motor vehicle with detection of a safety-critical state

ABSTRACT

An auxiliary heater for a motor vehicle equipped with a control device for controlling the operation of the auxiliary heater. In order to increase passenger protection in the motor vehicle, the control device is set up to detect a signal from at least one vehicle safety sensor, using the signal to detect the safety-critical state of the vehicle, and depending upon this detected status, ceases operation of the auxiliary heater.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to an auxiliary heater for a motor vehiclewith a control device for controlling the operation of the auxiliaryheater. Furthermore, the invention relates to a motor vehicle with onesuch auxiliary heater, and a process for control of one such auxiliaryheater.

[0003] 2. Description of Related Art

[0004] Heaters of this type are generally used to heat the air of thepassenger compartment or to heat the cooling water of an internalcombustion engine. In the former case, it is a so-called air heater, inthe latter case, a water heater.

[0005] In recent years, in vehicles, especially motor vehicles, it hasbeen possible to greatly improve passenger protection. The reason forimprovements is essentially that on the one hand it has been possible todetect an accident with electronic aids within milliseconds and on theother to make available active protection systems which instantaneouslyprotect the passengers against the external effects caused by anaccident. Active protection systems are mainly automatic belt tightenersand airbags, i.e., inflatable bodies with a pyrotechnic gas generatorwhich exist in the meantime in diverse versions.

[0006] German Patent DE 196 15 319 C1 discloses an air conditioningsystem of a motor vehicle with an evaporator in which, in the case ofaccident-induced damage to the evaporator, a quick closure closes theair channel which leads from the evaporator to the passengercompartments. The quick closure is preferably a small airbag.

[0007] The triggering mechanism for this small airbag can be the same asis used in airbags for passenger protection. However, in this airconditioning system, the actual escape of vapors cannot be prevented.

SUMMARY OF THE INVENTION

[0008] The object of the invention is to increase passenger protectionin motor vehicles which are equipped with an auxiliary heater.

[0009] This object is achieved in accordance with the invention in thatthe initially-mentioned type of auxiliary heater is provided with acontrol device that detects a signal from at least one motor vehiclesafety sensor, uses the signal to detect a safety-critical status of thevehicle, and depending upon this detected state, ceases operation of theauxiliary heater. The object is furthermore achieved with a motorvehicle in which such an auxiliary heater is installed. Finally, theobject is also achieved with a process for controlling such an auxiliaryheater in a vehicle with the following steps: detecting the safetystatus of the vehicle and controlling the auxiliary heater dependingupon the detected status.

[0010] The expression “vehicle safety sensors,” within the framework ofthis specification, encompasses those mechanisms which enable astatement about the safety of the vehicle. They are especiallymechanisms which are capable of determining a location, speed andacceleration or braking, rotational or tilting behavior, safety-criticalambient conditions or the status of individual assemblies of the motorvehicle.

[0011] The invention is based upon the finding that, in case of anaccident of a vehicle with a auxiliary heater, the heater can causevarious hazardous conditions. First, there is a danger that a fault willoccur in the control of the auxiliary heater, by which the auxiliaryheater in an extreme case can become overheated and damaged ordestroyed. Furthermore, there is the danger that the flame burning inthe auxiliary heater will ignite flammable fuels in the motor vehicle orin the surrounding area of the motor vehicle. This danger is especiallyhigh when fuel which is generally highly flammable or explosive hasescaped in an accident.

[0012] These dangers are averted in the auxiliary heater in accordancewith the invention by immediately ceasing the operation of the auxiliaryheater upon detection of an accident involving the motor vehicle. Inparticular, the auxiliary heater is turned off or actuating the heateris prevented. Thus, danger to the passengers of the motor vehicleoriginating from the auxiliary heater in case of an accident can beprevented.

[0013] In accordance with the invention, not only is an accident-inducedeffect (fire or explosion) on the passengers prevented, but also theaccident-induced effect itself is prevented. The major danger in anauxiliary heater originates from the flame burning in the device. Bystopping this flame in accordance with the invention, before seriousdamage to the auxiliary heater can occur due to an accident, it isensured that the auxiliary heater in the accident does not increase thedanger of an explosion as a result of escaped fuel.

[0014] In one exemplary embodiment of the invention, the auxiliaryheater includes a fuel feed with a shut-off device and the controldevice is set up to actuate the shut-off device immediately when asafety-critical state is detected. The shut-off device can be, forexample, a solenoid valve in a fuel delivery line. Alternatively, or inaddition to interrupting the fuel feed in accordance with the invention,the ignition mechanism which is generally present in conventionalauxiliary heaters is immediately shut down when an accident is detected.

[0015] Even when the fuel supply of the auxiliary heater is ceased, dueto so-called afterburning, there is still considerable development ofheat, and thus, further danger to the passengers. This hazard isprevented in another exemplary embodiment of the invention in which theauxiliary heater is provided with a combustion air feed and a controldevice is provided to immediately extinguish the flame in the auxiliaryheater by way of the combustion air feed when a safety-critical statusis detected.

[0016] The safety function of the auxiliary heater in accordance withthe invention can be implemented especially economically by setting upthe control device of the auxiliary heater to detect the signal of themotor vehicle safety sensor via a control device of the motor vehiclesafety system, for example, a belt tightener. These safety systems areoften standard equipment in conventional motor vehicles, and therefore,do not lead to additional costs. The control devices with respect tosignal exchange are often standardized by so-called interface protocols.Therefore, there is almost no additional cost when the control device ofthe auxiliary heater developed in accordance with the invention isinstalled.

[0017] To detect an accident of a vehicle which employs the auxiliaryheater in accordance with the invention, in an especially economicalmanner a position sensor, an acceleration sensor and/or an rpm sensor ofthe motor vehicle can be used. Alternatively, or in addition, theauxiliary heater itself can be provided with one such sensor.

[0018] Moreover, the safety of the motor vehicle can be improved byusing a tank cap sensor of the motor vehicle as a vehicle safety sensor.The tank cap sensor detects when the vehicle is being refueled, and istherefore in the state during which there is in turn an increasedexplosion risk.

[0019] Exchange of signals between the sensors and the control device ofthe auxiliary heater can take place especially economically according toone development of the invention via the vehicle data bus which ispresent anyway in the vehicle.

[0020] One embodiment of a motor vehicle auxiliary heater in accordancewith the invention is explained below with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The sole FIGURE shows a vehicle in accordance with the inventionwith an auxiliary heater.

DETAILED DESCRIPTION OF THE INVENTION

[0022] The vehicle 10 shown in FIG. 1 is provided with an auxiliaryheater 12 located in the engine compartment 14 of the vehicle 10. Theauxiliary heater 12 includes a burner 16 which receives a combination ofcombustion air from a combustion air fan 18 and liquid fuel from a fuelline 20 by way of the fuel pump 22. The fuel line 20 includes a solenoidvalve 24 downstream of the fuel pump 22 for shutting off flow throughthe pump, and thus, entry of fuel to the auxiliary heater 12. Downstreamof the burner 16 is a heat exchanger 26 in which the heat from a liquidor gaseous heat transfer medium is transferred to hot air. The hot airis conveyed with a hot air fan 28 into the passenger compartment 30. Theauxiliary heater 12 is provided with a control device 32 which iselectronically connected to the combustion air fan 18, fuel pump 22,solenoid valve 24 and hot air fan 28.

[0023] In the motor vehicle 10, a data bus 34 in the form of a CAN busis electronically connected to the control device 32. Furthermore, themotor vehicle 10 is provided with a plurality of sensors for sensing anoperation condition of the vehicle 10, for example, at least one of aposition sensor 36, an acceleration sensor 38, an rpm sensor 40 and atank cap sensor 42. Each position sensor 36, the acceleration sensor 38,the rpm sensor 40 and the tank cap sensor 42 may be each electronicallyconnected to the data bus 34 so as to send a signal to the motor vehicle10 about the safety status of the motor vehicle 10 through the data bus34. Thus, for example, acceleration of the vehicle 10 or an impact isimmediately recognized and reported. The tank cap sensor 42 reports whenthe tank cap is open; this generally means that the motor vehicle 10 isbeing fueled or fuel for the auxiliary heater 12 is being supplied. Thecontrol device 32 determines and evaluates the signals of the positionsensor 36, acceleration sensor 38, rpm sensor 40 and tank cap sensor 42when a safety-critical status of the motor vehicle 10 is detected. Inanother embodiment, the evaluation of the signals of the safety sensorsmay be transmitted to the safety system control device of the vehicle10, such as, for example, an airbag of a belt tightener which isdirectly coupled to the control device of the auxiliary heater 12.

[0024] If the control device 32 detects a safety-critical status, itinstantaneously ceases operation of the auxiliary heater 12. In doingso, especially the solenoid valve 24 is actuated, and thus, the fuelfeed line 20 is closed. Moreover, a flame in the burner 16 isextinguished by immediately stopping operation of the combustion air fan18.

[0025] Since the control device 32 shuts down the auxiliary heater 12within a very short time frame or prevents starting of the auxiliaryheater 12, in the case of an accident of the vehicle, there is no dangerthat the flame will ignite combustible substances in the auxiliaryheater 12 in the vehicle 10 or escaping fuel. It is also ensured thatthe auxiliary heater 12 itself is not overheated. If an accident shouldnot occur, there is no damage. The auxiliary heater 12 can be easilyrestarted after a certain time interval and especially after the safetystate of the vehicle has been re-checked.

What is claimed is:
 1. An auxiliary heater for a motor vehicle having aplurality of safety sensors for sensing a respective operating conditionof the motor vehicle, said auxiliary heater comprising: a control devicefor controlling operation of the auxiliary heater, said control devicebeing in electronic communication with the plurality of safety sensorsto receive a signal therefrom to detect safety-critical states of themotor vehicle, and to cease operation of the auxiliary heater upondetection of a safety-critical state.
 2. The auxiliary heater as claimedin claim 1, wherein said auxiliary heater further comprises a fuel feedfor providing fuel to said auxiliary heater, said fuel feed having ashut-off means for preventing entry of fuel to said auxiliary heater,said shut-off means being controlled by said control device so as tobecome actuated immediately upon detection of a safety-critical state.3. The auxiliary heater as claimed in claim 2, wherein said auxiliaryheater further comprises a combustion air feed for providing combustionair to said auxiliary heater, said combustion air feed being controlledby said control device so as to interrupt a flow of combustion air fromsaid combustion air feed to said auxiliary heater immediately upondetection of a safety-critical state.
 4. The auxiliary heater as claimedin claim 1, wherein said plurality of safety sensors comprises at leastone of a position sensor, an acceleration sensor, an rpm sensor and atank cap sensor.
 5. The auxiliary heater as claimed in claim 4, whereinsaid control device is in electronic communication with a safety systemcontrol device for the motor vehicle so as to receive a signal from atleast one of the position sensor, the acceleration sensor, the rpmsensor and the tank cap sensor via the safety system control device. 6.The auxiliary heater as claimed in claim 4, wherein said control deviceis in electronic communication with a data bus of the motor vehicle soas to receive a signal from at least one of the position sensor, theacceleration sensor, the rpm sensor and the tank cap sensor via the databus.
 7. A motor vehicle comprising: a plurality of safety sensors forsensing an operating condition of said motor vehicle; and an auxiliaryheater for providing heat to a compartment area of said motor vehicle,said auxiliary heater including a control device for controllingoperation of the auxiliary heater, said control device being inelectronic communication with the plurality of safety sensors to receivea signal therefrom to detect safety-critical states of the motorvehicle, and to cease operation of the auxiliary heater upon detectionof a safety-critical state.
 8. The motor vehicle as claimed in claim 7,wherein said auxiliary heater further comprises a fuel feed forproviding fuel to said auxiliary heater, said fuel feed having a shutoffmeans for preventing entry of the fuel to said auxiliary heater, saidshutoff means being controlled by said control device so as to becomeactuated immediately upon detection of a safety-critical state.
 9. Themotor vehicle as claimed in claim 8, wherein said auxiliary heaterfurther comprises a combustion air feed for providing combustion air tosaid auxiliary heater, said combustion air feed being controlled by saidcontrol device so as to interrupt a flow of combustion air from saidcombustion air feed to said auxiliary heater immediately upon detectionof a safety-critical state.
 10. The motor vehicle as claimed in claim 7,wherein said plurality of safety sensors comprises at least one of aposition sensor, an acceleration sensor, an rpm sensor and a tank capsensor.
 11. The motor vehicle as claimed in claim 10, further comprisinga safety system control device in electronic communication with saidcontrol device, said safety system control device being adapted toreceive signals from at least one of said position sensor, saidacceleration sensor, said rpm sensor and said tank cap sensor and tosend said signals to said control device.
 12. The motor vehicle asclaimed in claim 10, further comprising a data bus in electroniccommunication with said control device, said data bus being adapted toreceive signals from at least one of said position sensor, saidacceleration sensor, said rpm sensor and said tank cap sensor and tosend said signals to said control device.
 13. A process for controllingan auxiliary heater in a motor vehicle comprising the steps of:detecting a safety status of the motor vehicle; and controlling theauxiliary heater depending upon the detected safety status.
 14. Theprocess as claimed in claim 13, wherein the step of detecting a safetystatus of the motor vehicle comprises detecting at least one of aposition, acceleration and rpm of the motor vehicle.
 15. The process asclaimed in claim 13, wherein the step of detecting the safety status ofthe motor vehicle further comprises detecting the position of a fueltank cap of the motor vehicle.
 16. The process as claimed in claim 13,wherein the step of controlling the auxiliary heater comprises at leastone of shutting off the fuel feed of the auxiliary heater andinterrupting a flow of combustion air from the combustion air feed tocease operation of the auxiliary heater.